| // Copyright 2018 The Go Authors. All rights reserved. | 
 | // Use of this source code is governed by a BSD-style | 
 | // license that can be found in the LICENSE file. | 
 |  | 
 | // +build race | 
 |  | 
 | #include "go_asm.h" | 
 | #include "funcdata.h" | 
 | #include "textflag.h" | 
 | #include "tls_arm64.h" | 
 |  | 
 | // The following thunks allow calling the gcc-compiled race runtime directly | 
 | // from Go code without going all the way through cgo. | 
 | // First, it's much faster (up to 50% speedup for real Go programs). | 
 | // Second, it eliminates race-related special cases from cgocall and scheduler. | 
 | // Third, in long-term it will allow to remove cyclic runtime/race dependency on cmd/go. | 
 |  | 
 | // A brief recap of the arm64 calling convention. | 
 | // Arguments are passed in R0...R7, the rest is on stack. | 
 | // Callee-saved registers are: R19...R28. | 
 | // Temporary registers are: R9...R15 | 
 | // SP must be 16-byte aligned. | 
 |  | 
 | // When calling racecalladdr, R9 is the call target address. | 
 |  | 
 | // The race ctx, ThreadState *thr below, is passed in R0 and loaded in racecalladdr. | 
 |  | 
 | #define load_g \ | 
 | 	MRS_TPIDR_R0 \ | 
 | 	MOVD    runtime·tls_g(SB), R11 \ | 
 | 	ADD     R11, R0 \ | 
 | 	MOVD    0(R0), g | 
 |  | 
 | // func runtime·raceread(addr uintptr) | 
 | // Called from instrumented code. | 
 | TEXT	runtime·raceread(SB), NOSPLIT, $0-8 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	LR, R2 | 
 | 	// void __tsan_read(ThreadState *thr, void *addr, void *pc); | 
 | 	MOVD	$__tsan_read(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·RaceRead(addr uintptr) | 
 | TEXT	runtime·RaceRead(SB), NOSPLIT, $0-8 | 
 | 	// This needs to be a tail call, because raceread reads caller pc. | 
 | 	JMP	runtime·raceread(SB) | 
 |  | 
 | // func runtime·racereadpc(void *addr, void *callpc, void *pc) | 
 | TEXT	runtime·racereadpc(SB), NOSPLIT, $0-24 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	callpc+8(FP), R2 | 
 | 	MOVD	pc+16(FP), R3 | 
 | 	// void __tsan_read_pc(ThreadState *thr, void *addr, void *callpc, void *pc); | 
 | 	MOVD	$__tsan_read_pc(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·racewrite(addr uintptr) | 
 | // Called from instrumented code. | 
 | TEXT	runtime·racewrite(SB), NOSPLIT, $0-8 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	LR, R2 | 
 | 	// void __tsan_write(ThreadState *thr, void *addr, void *pc); | 
 | 	MOVD	$__tsan_write(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·RaceWrite(addr uintptr) | 
 | TEXT	runtime·RaceWrite(SB), NOSPLIT, $0-8 | 
 | 	// This needs to be a tail call, because racewrite reads caller pc. | 
 | 	JMP	runtime·racewrite(SB) | 
 |  | 
 | // func runtime·racewritepc(void *addr, void *callpc, void *pc) | 
 | TEXT	runtime·racewritepc(SB), NOSPLIT, $0-24 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	callpc+8(FP), R2 | 
 | 	MOVD	pc+16(FP), R3 | 
 | 	// void __tsan_write_pc(ThreadState *thr, void *addr, void *callpc, void *pc); | 
 | 	MOVD	$__tsan_write_pc(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·racereadrange(addr, size uintptr) | 
 | // Called from instrumented code. | 
 | TEXT	runtime·racereadrange(SB), NOSPLIT, $0-16 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	size+8(FP), R2 | 
 | 	MOVD	LR, R3 | 
 | 	// void __tsan_read_range(ThreadState *thr, void *addr, uintptr size, void *pc); | 
 | 	MOVD	$__tsan_read_range(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·RaceReadRange(addr, size uintptr) | 
 | TEXT	runtime·RaceReadRange(SB), NOSPLIT, $0-16 | 
 | 	// This needs to be a tail call, because racereadrange reads caller pc. | 
 | 	JMP	runtime·racereadrange(SB) | 
 |  | 
 | // func runtime·racereadrangepc1(void *addr, uintptr sz, void *pc) | 
 | TEXT	runtime·racereadrangepc1(SB), NOSPLIT, $0-24 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	size+8(FP), R2 | 
 | 	MOVD	pc+16(FP), R3 | 
 | 	ADD	$4, R3	// pc is function start, tsan wants return address. | 
 | 	// void __tsan_read_range(ThreadState *thr, void *addr, uintptr size, void *pc); | 
 | 	MOVD	$__tsan_read_range(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·racewriterange(addr, size uintptr) | 
 | // Called from instrumented code. | 
 | TEXT	runtime·racewriterange(SB), NOSPLIT, $0-16 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	size+8(FP), R2 | 
 | 	MOVD	LR, R3 | 
 | 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc); | 
 | 	MOVD	$__tsan_write_range(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // func runtime·RaceWriteRange(addr, size uintptr) | 
 | TEXT	runtime·RaceWriteRange(SB), NOSPLIT, $0-16 | 
 | 	// This needs to be a tail call, because racewriterange reads caller pc. | 
 | 	JMP	runtime·racewriterange(SB) | 
 |  | 
 | // func runtime·racewriterangepc1(void *addr, uintptr sz, void *pc) | 
 | TEXT	runtime·racewriterangepc1(SB), NOSPLIT, $0-24 | 
 | 	MOVD	addr+0(FP), R1 | 
 | 	MOVD	size+8(FP), R2 | 
 | 	MOVD	pc+16(FP), R3 | 
 | 	ADD	$4, R3	// pc is function start, tsan wants return address. | 
 | 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc); | 
 | 	MOVD	$__tsan_write_range(SB), R9 | 
 | 	JMP	racecalladdr<>(SB) | 
 |  | 
 | // If addr (R1) is out of range, do nothing. | 
 | // Otherwise, setup goroutine context and invoke racecall. Other arguments already set. | 
 | TEXT	racecalladdr<>(SB), NOSPLIT, $0-0 | 
 | 	load_g | 
 | 	MOVD	g_racectx(g), R0 | 
 | 	// Check that addr is within [arenastart, arenaend) or within [racedatastart, racedataend). | 
 | 	MOVD	runtime·racearenastart(SB), R10 | 
 | 	CMP	R10, R1 | 
 | 	BLT	data | 
 | 	MOVD	runtime·racearenaend(SB), R10 | 
 | 	CMP	R10, R1 | 
 | 	BLT	call | 
 | data: | 
 | 	MOVD	runtime·racedatastart(SB), R10 | 
 | 	CMP	R10, R1 | 
 | 	BLT	ret | 
 | 	MOVD	runtime·racedataend(SB), R10 | 
 | 	CMP	R10, R1 | 
 | 	BGT	ret | 
 | call: | 
 | 	JMP	racecall<>(SB) | 
 | ret: | 
 | 	RET | 
 |  | 
 | // func runtime·racefuncenterfp(fp uintptr) | 
 | // Called from instrumented code. | 
 | // Like racefuncenter but doesn't passes an arg, uses the caller pc | 
 | // from the first slot on the stack | 
 | TEXT	runtime·racefuncenterfp(SB), NOSPLIT, $0-0 | 
 | 	MOVD	0(RSP), R9 | 
 | 	JMP	racefuncenter<>(SB) | 
 |  | 
 | // func runtime·racefuncenter(pc uintptr) | 
 | // Called from instrumented code. | 
 | TEXT	runtime·racefuncenter(SB), NOSPLIT, $0-8 | 
 | 	MOVD	callpc+0(FP), R9 | 
 | 	JMP	racefuncenter<>(SB) | 
 |  | 
 | // Common code for racefuncenter/racefuncenterfp | 
 | // R9 = caller's return address | 
 | TEXT	racefuncenter<>(SB), NOSPLIT, $0-0 | 
 | 	load_g | 
 | 	MOVD	g_racectx(g), R0	// goroutine racectx | 
 | 	MOVD	R9, R1 | 
 | 	// void __tsan_func_enter(ThreadState *thr, void *pc); | 
 | 	MOVD	$__tsan_func_enter(SB), R9 | 
 | 	BL	racecall<>(SB) | 
 | 	RET | 
 |  | 
 | // func runtime·racefuncexit() | 
 | // Called from instrumented code. | 
 | TEXT	runtime·racefuncexit(SB), NOSPLIT, $0-0 | 
 | 	load_g | 
 | 	MOVD	g_racectx(g), R0	// race context | 
 | 	// void __tsan_func_exit(ThreadState *thr); | 
 | 	MOVD	$__tsan_func_exit(SB), R9 | 
 | 	JMP	racecall<>(SB) | 
 |  | 
 | // Atomic operations for sync/atomic package. | 
 | // R3 = addr of arguments passed to this function, it can | 
 | // be fetched at 40(RSP) in racecallatomic after two times BL | 
 | // R0, R1, R2 set in racecallatomic | 
 |  | 
 | // Load | 
 | TEXT	sync∕atomic·LoadInt32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic32_load(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·LoadInt64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic64_load(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·LoadUint32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·LoadInt32(SB) | 
 |  | 
 | TEXT	sync∕atomic·LoadUint64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·LoadInt64(SB) | 
 |  | 
 | TEXT	sync∕atomic·LoadUintptr(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·LoadInt64(SB) | 
 |  | 
 | TEXT	sync∕atomic·LoadPointer(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·LoadInt64(SB) | 
 |  | 
 | // Store | 
 | TEXT	sync∕atomic·StoreInt32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic32_store(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·StoreInt64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic64_store(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·StoreUint32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·StoreInt32(SB) | 
 |  | 
 | TEXT	sync∕atomic·StoreUint64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·StoreInt64(SB) | 
 |  | 
 | TEXT	sync∕atomic·StoreUintptr(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·StoreInt64(SB) | 
 |  | 
 | // Swap | 
 | TEXT	sync∕atomic·SwapInt32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic32_exchange(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·SwapInt64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic64_exchange(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·SwapUint32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·SwapInt32(SB) | 
 |  | 
 | TEXT	sync∕atomic·SwapUint64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·SwapInt64(SB) | 
 |  | 
 | TEXT	sync∕atomic·SwapUintptr(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·SwapInt64(SB) | 
 |  | 
 | // Add | 
 | TEXT	sync∕atomic·AddInt32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic32_fetch_add(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	MOVW	add+8(FP), R0	// convert fetch_add to add_fetch | 
 | 	MOVW	ret+16(FP), R1 | 
 | 	ADD	R0, R1, R0 | 
 | 	MOVW	R0, ret+16(FP) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·AddInt64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic64_fetch_add(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	MOVD	add+8(FP), R0	// convert fetch_add to add_fetch | 
 | 	MOVD	ret+16(FP), R1 | 
 | 	ADD	R0, R1, R0 | 
 | 	MOVD	R0, ret+16(FP) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·AddUint32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·AddInt32(SB) | 
 |  | 
 | TEXT	sync∕atomic·AddUint64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·AddInt64(SB) | 
 |  | 
 | TEXT	sync∕atomic·AddUintptr(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·AddInt64(SB) | 
 |  | 
 | // CompareAndSwap | 
 | TEXT	sync∕atomic·CompareAndSwapInt32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic32_compare_exchange(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·CompareAndSwapInt64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	MOVD	$__tsan_go_atomic64_compare_exchange(SB), R9 | 
 | 	BL	racecallatomic<>(SB) | 
 | 	RET | 
 |  | 
 | TEXT	sync∕atomic·CompareAndSwapUint32(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·CompareAndSwapInt32(SB) | 
 |  | 
 | TEXT	sync∕atomic·CompareAndSwapUint64(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·CompareAndSwapInt64(SB) | 
 |  | 
 | TEXT	sync∕atomic·CompareAndSwapUintptr(SB), NOSPLIT, $0 | 
 | 	GO_ARGS | 
 | 	JMP	sync∕atomic·CompareAndSwapInt64(SB) | 
 |  | 
 | // Generic atomic operation implementation. | 
 | // R9 = addr of target function | 
 | TEXT	racecallatomic<>(SB), NOSPLIT, $0 | 
 | 	// Set up these registers | 
 | 	// R0 = *ThreadState | 
 | 	// R1 = caller pc | 
 | 	// R2 = pc | 
 | 	// R3 = addr of incoming arg list | 
 |  | 
 | 	// Trigger SIGSEGV early. | 
 | 	MOVD	40(RSP), R3	// 1st arg is addr. after two times BL, get it at 40(RSP) | 
 | 	MOVD	(R3), R13	// segv here if addr is bad | 
 | 	// Check that addr is within [arenastart, arenaend) or within [racedatastart, racedataend). | 
 | 	MOVD	runtime·racearenastart(SB), R10 | 
 | 	CMP	R10, R3 | 
 | 	BLT	racecallatomic_data | 
 | 	MOVD	runtime·racearenaend(SB), R10 | 
 | 	CMP	R10, R3 | 
 | 	BLT	racecallatomic_ok | 
 | racecallatomic_data: | 
 | 	MOVD	runtime·racedatastart(SB), R10 | 
 | 	CMP	R10, R3 | 
 | 	BLT	racecallatomic_ignore | 
 | 	MOVD	runtime·racedataend(SB), R10 | 
 | 	CMP	R10, R3 | 
 | 	BGE	racecallatomic_ignore | 
 | racecallatomic_ok: | 
 | 	// Addr is within the good range, call the atomic function. | 
 | 	load_g | 
 | 	MOVD	g_racectx(g), R0	// goroutine context | 
 | 	MOVD	16(RSP), R1	// caller pc | 
 | 	MOVD	R9, R2	// pc | 
 | 	ADD	$40, RSP, R3 | 
 | 	JMP	racecall<>(SB)	// does not return | 
 | racecallatomic_ignore: | 
 | 	// Addr is outside the good range. | 
 | 	// Call __tsan_go_ignore_sync_begin to ignore synchronization during the atomic op. | 
 | 	// An attempt to synchronize on the address would cause crash. | 
 | 	MOVD	R9, R20	// remember the original function | 
 | 	MOVD	$__tsan_go_ignore_sync_begin(SB), R9 | 
 | 	load_g | 
 | 	MOVD	g_racectx(g), R0	// goroutine context | 
 | 	BL	racecall<>(SB) | 
 | 	MOVD	R20, R9	// restore the original function | 
 | 	// Call the atomic function. | 
 | 	// racecall will call LLVM race code which might clobber R28 (g) | 
 | 	load_g | 
 | 	MOVD	g_racectx(g), R0	// goroutine context | 
 | 	MOVD	16(RSP), R1	// caller pc | 
 | 	MOVD	R9, R2	// pc | 
 | 	ADD	$40, RSP, R3	// arguments | 
 | 	BL	racecall<>(SB) | 
 | 	// Call __tsan_go_ignore_sync_end. | 
 | 	MOVD	$__tsan_go_ignore_sync_end(SB), R9 | 
 | 	MOVD	g_racectx(g), R0	// goroutine context | 
 | 	BL	racecall<>(SB) | 
 | 	RET | 
 |  | 
 | // func runtime·racecall(void(*f)(...), ...) | 
 | // Calls C function f from race runtime and passes up to 4 arguments to it. | 
 | // The arguments are never heap-object-preserving pointers, so we pretend there are no arguments. | 
 | TEXT	runtime·racecall(SB), NOSPLIT, $0-0 | 
 | 	MOVD	fn+0(FP), R9 | 
 | 	MOVD	arg0+8(FP), R0 | 
 | 	MOVD	arg1+16(FP), R1 | 
 | 	MOVD	arg2+24(FP), R2 | 
 | 	MOVD	arg3+32(FP), R3 | 
 | 	JMP	racecall<>(SB) | 
 |  | 
 | // Switches SP to g0 stack and calls (R9). Arguments already set. | 
 | TEXT	racecall<>(SB), NOSPLIT, $0-0 | 
 | 	MOVD	g_m(g), R10 | 
 | 	// Switch to g0 stack. | 
 | 	MOVD	RSP, R19	// callee-saved, preserved across the CALL | 
 | 	MOVD	m_g0(R10), R11 | 
 | 	CMP	R11, g | 
 | 	BEQ	call	// already on g0 | 
 | 	MOVD	(g_sched+gobuf_sp)(R11), R12 | 
 | 	MOVD	R12, RSP | 
 | call: | 
 | 	BL	R9 | 
 | 	MOVD	R19, RSP | 
 | 	RET | 
 |  | 
 | // C->Go callback thunk that allows to call runtime·racesymbolize from C code. | 
 | // Direct Go->C race call has only switched SP, finish g->g0 switch by setting correct g. | 
 | // The overall effect of Go->C->Go call chain is similar to that of mcall. | 
 | // R0 contains command code. R1 contains command-specific context. | 
 | // See racecallback for command codes. | 
 | TEXT	runtime·racecallbackthunk(SB), NOSPLIT|NOFRAME, $0 | 
 | 	// Handle command raceGetProcCmd (0) here. | 
 | 	// First, code below assumes that we are on curg, while raceGetProcCmd | 
 | 	// can be executed on g0. Second, it is called frequently, so will | 
 | 	// benefit from this fast path. | 
 | 	CBNZ	R0, rest | 
 | 	MOVD	g, R13 | 
 | 	load_g | 
 | 	MOVD	g_m(g), R0 | 
 | 	MOVD	m_p(R0), R0 | 
 | 	MOVD	p_raceprocctx(R0), R0 | 
 | 	MOVD	R0, (R1) | 
 | 	MOVD	R13, g | 
 | 	JMP	(LR) | 
 | rest: | 
 | 	// Save callee-saved registers (Go code won't respect that). | 
 | 	// 8(RSP) and 16(RSP) are for args passed through racecallback | 
 | 	SUB	$112, RSP | 
 | 	MOVD	LR, 0(RSP) | 
 | 	STP	(R19, R20), 24(RSP) | 
 | 	STP	(R21, R22), 40(RSP) | 
 | 	STP	(R23, R24), 56(RSP) | 
 | 	STP	(R25, R26), 72(RSP) | 
 | 	STP	(R27,   g), 88(RSP) | 
 | 	// Set g = g0. | 
 | 	// load_g will clobber R0, Save R0 | 
 | 	MOVD	R0, R13 | 
 | 	load_g | 
 | 	// restore R0 | 
 | 	MOVD	R13, R0 | 
 | 	MOVD	g_m(g), R13 | 
 | 	MOVD	m_g0(R13), R14 | 
 | 	CMP	R14, g | 
 | 	BEQ	noswitch	// branch if already on g0 | 
 | 	MOVD	R14, g | 
 |  | 
 | 	MOVD	R0, 8(RSP)	// func arg | 
 | 	MOVD	R1, 16(RSP)	// func arg | 
 | 	BL	runtime·racecallback(SB) | 
 |  | 
 | 	// All registers are smashed after Go code, reload. | 
 | 	MOVD	g_m(g), R13 | 
 | 	MOVD	m_curg(R13), g	// g = m->curg | 
 | ret: | 
 | 	// Restore callee-saved registers. | 
 | 	MOVD	0(RSP), LR | 
 | 	LDP	24(RSP), (R19, R20) | 
 | 	LDP	40(RSP), (R21, R22) | 
 | 	LDP	56(RSP), (R23, R24) | 
 | 	LDP	72(RSP), (R25, R26) | 
 | 	LDP	88(RSP), (R27,   g) | 
 | 	ADD	$112, RSP | 
 | 	JMP	(LR) | 
 |  | 
 | noswitch: | 
 | 	// already on g0 | 
 | 	MOVD	R0, 8(RSP)	// func arg | 
 | 	MOVD	R1, 16(RSP)	// func arg | 
 | 	BL	runtime·racecallback(SB) | 
 | 	JMP	ret | 
 |  | 
 | // tls_g, g value for each thread in TLS | 
 | GLOBL runtime·tls_g+0(SB), TLSBSS+DUPOK, $8 |